This research project aims at developing an ultrasensitive gas chromatographic-mass spectrometric (GC-MS) method for rapid and specific diagnosis of pneumococcal pneumonias, bacterial endocarditis and tuberculosis in man. From previous work, it was indicated that specific products or components of infectious agents are detectable in serum, urine or tissues of patients and experimental animals by gas chromatographic means. The use of GC-MS sytem is, therefore, planned to detect and to identfy the specific metabolites of streptococcal, pneumococcal and mycobacterial strins in their specific culture media, and in body fluids of the infected hosts. The results show that two specific peaks were present in the cultures of streptococci, in sera of rabbits with experimental endocarditis and in sera of patients with streptococcal endocarditis. In patients with negative blood cultures, streptococcal endocarditis was diagnosed based upon the presence of the two specific peaks. The peaks were not present in control sera and cultures and also with other bacteria examined. Another specific peak (compound) was present in all the samples associated with pneumococcal infection. Further evaluations of GC technique for separation and MS technique for identification of specific bacterial compounds should establish this method as a useful tool in clinical pathology and in epidemiology. BIBLIOGRAPHIC REFERENCES: Mitruka, B.M., Rapid Automated Identification of Microorganisms in Clinical Specimens by Gas Chromatography, in, New Approaches to the Identification of Microorganisms (Chapter 8, pp. 123-154), Carl-G Heden and T. Illni (eds.), John Wiley and Sons, Inc., New York, 1975. Mitruka, B.M., Gas Chromatographic Applications in Microbiology and Medicine, John Wiley and Sons, Inc., New York, 1975.